The present invention relates to a liquid crystal display, and more particularly, to a liquid crystal display of a so-called active-matrix type.
The liquid crystal display of the active-matrix type is provided with a plurality of gate signal lines, which extend Act in the X direction and are arranged in parallel in the Y direction, and a plurality of drain signal lines, which extend in the Y direction and are arranged in parallel in the X direction, on a liquid-crystal-side surface of one of two substrates which are arranged to face each other in an opposed manner while inserting liquid crystal disposed therebetween. A region which is surrounded by two neighboring gate signal lines and two neighboring drain signal lines defines a pixel region.
Each pixel region is provided with a switching element which is driven by scanning signals from one-side via a gate signal line and a pixel electrode to which video signals are supplied from one-side via a drain signal line through the switching element.
On a liquid-crystal-side surface of the other substrate, of the pair of substrates, pixel electrodes are formed which face the pixel electrodes on the one substrate in an opposed manner and constitute capacitors. By generating an electric field between the pixel electrodes which are respectively formed on the two substrates, the light transmittivity of the liquid crystal is controlled.
Further, on a periphery of the liquid-crystal-side surface of one substrate, a semiconductor integrated circuit (IC chip), which constitutes a scanning signal driving circuit, and a semiconductor integrated circuit (IC chip) which constitutes a video signal driving circuit, are directly mounted with bump forming surfaces thereof directed downwardly (face down) (COG: Chip On Glass). On the substrate on which the IC chips are mounted, signal lines which correspond to the IC chips are extended to positions which face respective output bumps of the IC chips and terminals which are connected with the output bumps are formed on the extended portions or extensions.
Recently, there has been a demand for the liquid crystal displays to exhibit an enhancement of the definition thereof. To satisfy this requirement, the number of pixels has been increased and the number of gate signal lines and drain signal lines has been increased correspondingly.
As bumps (particularly, output bumps) which are connected to the signal lines of the semiconductor integrated circuit, there is a known arrangement of bumps which provides for an increased number of bumps, wherein the bumps are constituted of a first group of bumps which are arranged at the signal-line side and a second group of bumps which are arranged at the side remote from the signal lines.
In a liquid crystal display of the COG type, the semiconductor integrated circuits are fixedly secured to the substrate by way of anisotropic conductive layers and are, respectively connected to corresponding terminals. Japanese Laid-open Patent Publication 81635/2000 discloses such a technique.
However, in this case, the connection resistance between the respective bumps which constitute the second group of bumps and the respective terminals connected to these respective bumps becomes larger than the connection resistance between the respective bumps which constitute the first group of bumps and the respective terminals connected to these bumps. Accordingly, in a worst case, there arises a possibility that the second group of bumps may suffer from a connection failure.
The present invention, which has been made in view of the above-mentioned circumstances, is able to provide a liquid crystal display which can ensure the connection between semiconductor integrated circuits and signal lines mounted on the liquid crystal display.
A liquid crystal display according to the present invention is provided with a plurality of signal lines which respectively have connection terminals and a semiconductor chip which is connected to respective terminals of a plurality of signal lines on a liquid-crystal-side surface of one of two substrates which are arranged to face each other with liquid crystal being disposed therebetween. The semiconductor chip includes a plurality of bumps which are respectively connected to corresponding terminals of respective signal lines through the anisotropic conductive layer. Further, a plurality of these bumps constitute at least groups of bumps arranged in two rows. The bumps include a first group of bumps, which are arranged at a side close to an end portion of the semiconductor chip, and a second group of bumps, which are arranged at a side remote from the end portion, wherein a contact area between the respective bumps of the second group of bumps and the signal lines is set to be larger than a contact area between the respective bumps of the first group of bumps and the signal lines.
The liquid crystal display according to the present invention has a resistance value at the contact portion between the respective bumps of the second group of bumps and the signal lines which is reduced to a level substantially equal to the resistance value at the contact portion between the respective bumps of the first group of bumps and the signal lines.
Accordingly, it becomes possible to eliminate the phenomenon in which the connection resistance between the respective bumps which constitute the second group of bumps and the signal lines which are connected to these bumps is increased, or a connection failure occurs in the worst case.